L293D

const int izq = 13;  
const int der = 12;  
const int m1 =  3;  
const int m2 =  2;  
const int v =  9;    

int b1 = 0;
int b2 = 0;
void setup() {
  pinMode(m1, OUTPUT);  
  pinMode(m2, OUTPUT);  
  pinMode(v, OUTPUT);  
  pinMode(izq, INPUT);
  pinMode(der, INPUT);  

  digitalWrite(m1, LOW);
  digitalWrite(m2, LOW);
  digitalWrite(v, LOW);
}

void loop(){
 
  b1 = digitalRead(izq);
  if (b1 == HIGH) {
    digitalWrite(v, LOW);  
    digitalWrite(m1, HIGH);
    digitalWrite(m2, LOW);
    digitalWrite(v, HIGH);
  }
 
 
  b2 = digitalRead(der);
  if (b2 == HIGH) {
    digitalWrite(v, LOW);  
    digitalWrite(m1, LOW);
    digitalWrite(m2, HIGH);
    digitalWrite(v, HIGH);
 
  }

}